Israel occupied the Golan Heights militarily in 1967, and started building settlements there almost immediately. In 1981, Israel formally annexed Golan, though this is not recognized internationally. Legally, the Golan Heights are part of Syria, occupied by Israel.

Since the annexation in 1981, Israeli officials have regularly denied publicly they’d be willing to give the territory up, though there were reports before the Syrian War that a deal had been broached on giving the Golan back to Syria as part of a broader peace deal.

Since then, Israel has started some lucrative oil projects in the Golan Heights, which further make returning the territory to Syria unlikely, though the lack of international endorsement for the annexation means this is a territory issue that’s going to be a recurring issue in the future.